1. Field of the Invention
The present invention relates generally to a system and method for speaker recognition. In particular, although not exclusively, the present invention relates to the use of uncertainty modelling in automatic speaker verification systems.
2. Discussion of the Background Art
In recent years, the interaction between computing systems and humans has been greatly enhanced by the use of speech recognition software. However, the introduction of speech based interfaces has presented the need for identifying and authenticating speakers to improve reliability and provide additional security for speech based and related applications. Various forms of speaker recognition systems have been utilised in such areas as banking and finance, electronic signatures and forensic science.
The problem with most speaker verification systems is that they do not provide a speaker recognition algorithm which performs reliably under adverse communications conditions, such as limited enrolment speech, channel mismatch, speech degradation and additive noise, which typically occur over telephony networks.
One major development this field which resulted significant improvements in the reliability of such speaker verification systems was the introduction of the universal background model (UBM). The UBM generally serves two distinctly different roles in a typical speaker verification system. Firstly, as the name suggests, as a background model representing all other speakers other than the claimant during a verification trial. Secondly, and more importantly, the UBM provides the information used to determine the prior distribution of speaker model parameters for MAP adaptation training. A speaker verification system which employs a UBM is discussed in the applicant's earlier filed International Application WO2005/055200 entitled “Model Adaptation System and Method for Speaker Recognition” the contents of which are herein incorporated by reference.
Since development of the system and method discussed in WO2005/055200 the applicant has realised that further improvements to the reliability of such speaker verification systems can be realised